The splitting of light from a quasar though a lens.

by Budgieye moderator

enter image description here

This image is from the Spotter's Guide, showing quasar points balanced on both sides of nucleus.

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http://talk.spacewarps.org/#/subjects/ASW0001g7d

This is a training image, a simulation, a #sim.I thought this could not be a #double quasar, because the two quasar points were not centered around the nucleus of the galaxy.

Is this simulation a true representation of what can be expected, or is it a #simfail?

Posted July 11, 2013 4:38 AM

by Budgieye moderator

From Spotter's Guide

Below the examples show quasars lensed by a single galaxy, quasars lensed by a galaxy group are even rarer. To date, only three quasars lensed by a galaxy group/cluster have been found.

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Image of Einstein cross, quadruply lensed quasar, #quad from Spotter's guide.

A few months ago psaha gave me a test question, why does a #quad quasar have 4 points.

I know that quasar light won't spread out as an arc, because it is a point source of light. (A lensed galaxy is an extended source of light and will spread out in an arc)

Is it because the light from a quasar passed through two lenses, thus creating 4 points of light? The Spotter's guide says that the quasar is lensed by a group, which would imply more than one lens. I see only one galaxy. Is this image real?

Posted July 11, 2013 4:59 AM

by Budgieye moderator

enter image description here

http://talk.spacewarps.org/#/subjects/ASW0004id9

Third question, how dim can we expect quasar points to be. There are many images with dim blue stars being posted in Recent. In the SDSS telescope survey, quasars were always bright enough to look like a small bright star.

When I look at a blue fuzzy area, I ask myself "If that was further away from the galaxy, would I think it was usual?"

Can I assume that quasars points must always be small and bright, like the images in Spotter's Guide?

Can the light from one or more of the quasar points be blocked by the thicker parts of the galaxy, producing a "single double" or a "triple quad" ?

Posted July 11, 2013 5:15 AM

by c_cld

Example of known catalogued quasars in CFTHLS Wide fields cross-matched with VII/258/vv10 table
order by spectroscopic redshift

SDSS J140604.24+572956.6 1237659326016585782 z 0.326

1237659326016585782

SDSS J222220.97+005709.4 1237678617407128166 z 0.770

1237678617407128166

SDSS J135711.23+555804.9 1237661418748248217 z 0.940

1237661418748248217

SDSS J022706.81-090717.1 1237653500969418799 z 0.960

1237653500969418799

SDSS J140954.00+544414.4 1237661387604492350 z 1.050

1237661387604492350

SDSS J140326.91+561307.3 1237659324406038647 z 1.074

1237659324406038647

SDSS J022600.02-035954.4 1237679254672375924 z(~) 1.095

1237679254672375924

SDSS J141059.36+570829.4 1237659326016913547 z 1.580

1237659326016913547

SDSS J221227.74+005140.7 1237663480332419340 z 1.773

1237663480332419340

SDSS J022914.12-075737.3 1237673701279203406 z 2.488

1237673701279203406

SDSS J143022.34+565712.5 1237659327091769723 z 4.561

1237659327091769723

SDSS J023137.64-072854.4 1237673701279531827 z 5.421

1237673701279531827

I found that these examples have little similarity with sims or with objects posted on #quasar hashtag :-😉

Posted July 11, 2013 7:56 AM

by c_cld in response to Budgieye's comment.

On #quad it's interesting to learn the case of A quadruply imaged quasar with an optical Einstein ring
candidate: 1RXS J113155.4−123155 arXiv:astro-ph/0307345 from D. Sluse et al.

Abstract. We report the discovery of a new quadruply imaged quasar surrounded by an optical Einstein ring candidate. Spectra of the different components of 1RXS J113155.4−123155 reveal a source at z = 0.658. Up to now, this object is the closest known gravitationally lensed quasar. The lensing galaxy is clearly detected. Its redshift is measured to be z = 0.295.

conclusion quote:
'This bright system brings together rare properties (i.e. quad, bright optical Einstein ring, small redshift, high amplification), nearly unique among the known gravitational lens systems. These features make 1RXS J113155.4−123155 a very promising astrophysical laboratory for future investigations, including the possibility for an independent determination of the Hubble parameter H0 based on time delay measurements.'

Posted July 11, 2013 9:40 AM

by c_cld in response to Budgieye's comment.

about the third question on dim quasar:

the faintest cross-match is SDSS J021827.30-053457.5 1237679321787400654 redshift: 2.583

1237679321787400654

CFHTLS gri 60 arcseconds square

1237679321787400654

somewhat noisy, could get a better contrast in Space Warps, particulary in bluer 😃

Posted July 11, 2013 8:26 PM

by c_cld in response to Budgieye's comment.

2nd part of third question: blocked images of lensed object (not restricted to AGN/QSO, could be galaxy)

see post of "Einstein Cross"

SDSS J141735.73+522646.3 1237661416065663689 z lens= 0.811
z source = 3.4

#quad by HST view or by ugr img form Terapix, but triple in gri.

Only double within frame like those presented here (60" square):

Einstein Cross

results vary with resolution but depend also on image processing and zooming capabilities within noise limitations and pixelization!

Posted July 11, 2013 9:03 PM

by Budgieye moderator

Thank you for your hard work, c_cld. I will get back to this in a few days.

Posted July 14, 2013 6:16 AM

by c_cld

Illustration of a background quasar 1237656567583670573 (z spec. 2.857) in the arms of a foreground spiral 1237656567583670572 (z spec.0.095)

1237656567583670573 SDSS

1237656567583670573 CFHTLS 60 arcseconds square

seen from terapix

1237656567583670573 gri
ugr

#overlap 😃

ASW0008nul

Posted July 14, 2013 6:31 PM

by Budgieye moderator

Some of the quasar points are fuzzier than I would have hoped, though some are small bright with clean edges. It certainly shows the importance of colour images.

Posted July 23, 2013 6:29 AM

by Budgieye moderator

Looking at your analysis of colour of Hubble lens candidate, HST14176+5226 in the Galaxy Zoo forum,

you presented the gri image of the candidate, such as we would see in our SpaceWarps image

enter image description here

I am amazed at how pink or light blue the arcs are. However, this is still only a lens candidate, not a proven lens. Also, they do say that the points look like arcs (ie from a lensed galaxy) not quasar points (ie from a quasar)

Posted July 27, 2013 6:22 AM

by Budgieye moderator

Proven lensed quasars copied from my spotter's guide on Galaxy Zoo Forum http://www.galaxyzooforum.org/index.php?topic=275811.0. I have tried to match SDSS image size and magnification for the Recent page (magnification 0.2 and image size 360 pix). CFHT will have sharper images, but the colour and size should be about the same.

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http://cas.sdss.org/astro/en/tools/explore/obj.asp?id=587729388218679312

z=1.41 Those two “stars” are lensed light from one quasar.
This object is the first example of a gravitational lens
the massive lensing elliptical galaxy, seen between them,
lies at redshift z = 0.355 (3.7 billion ly)
The distant quasar lies at redshift z = 1.41 (8.7 billion ly)
1979 The Twin Quasar http://adsabs.harvard.edu/cgi-bin/bib_query?1979Nat...279..381W
"Q0957+561 A, B: Twin Quasistellar Objects or Gravitational Lens?

They are bright enough using the SDSS telescope, so should be even brighter in the CFHT telescope.

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http://cas.sdss.org/dr7/en/tools/explore/obj.asp?id=588297863111180358

z=1.73 2003 http://arxiv.org/abs/astro-ph/0312427
"A gravitationally lensed quasar with quadruple images separated by 14.62arcseconds"

There have been many lensed quasars found, but this has a wide separation between lensed galaxies
The orange massive galaxy has z= 0.67
It has two nearby companions at z=0.67
The lensed quasar is in 4 arcs, at z=1.73

These quasar points are a far away from the lensing galaxy, 14.62 " , say 15" is about a quarter of the way across one of our images (60").

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http://cas.sdss.org/astro/en/tools/explore/obj.asp?id=588017726004396138

z=2.024 The triple quasar Q1115+080A, B, C - A quintuple gravitational lens image
http://adsabs.harvard.edu/cgi-bin/bib_query?1979Nat...279..381W
PG 1115+080 A gravitational cloverleaf Hazard, et al 1984, ApJ, 282
Astronomy Picture of the Day March 31, 1999
and Chandra

I believe that lens arcs and points are always odd numbers. So a quad must have another point hidden by the lensing galaxy.

enter image description here

http://cas.sdss.org/dr7/en/tools/explore/obj.asp?ra=08:20:16.1 &dec= +08:12:16

z=2.024

2009 SDSS J082016.11+081215.9 http://arxiv.org/abs/0906.2647
"A new gravitational lens from the MUSCLES survey: ULAS J082016.1+081216"
The lens galaxy as a faint red object of redshift 0.803
The lensed quasar has a double image (not really visible in SDSS) and z= 2.024

I wouldn't guess that this was a lens

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http://cas.sdss.org/astro/en/tools/chart/chart.asp?ra=124.99826353&dec=53.94036891

z=2.237 2009 SDSS J0819+5356
red lensing galaxy z=0.294
lensed quasar, blue 4" to north west, z=2.237,
listed as a star on NED
spectrum evidently a mix of the red galaxy and the quasar
“Five New High-Redshift Quasar Lenses from the Sloan Digital Sky Survey”
2009 http://arxiv.org/abs/0809.0912

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